1. Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display and a driving method thereof. More particularly, the present invention relates to an organic light emitting diode display for quickly compensating deterioration of an organic light emitting diode and displaying an image with uniform luminance irrespective of a threshold voltage and mobility of a driving transistor, and a driving method thereof.
2. Description of the Related Art
Various kinds of flat display devices that are capable of reducing detriments of cathode ray tubes (CRT), such as their heavy weight and large size, have been developed in recent years. Such flat display devices include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and organic light emitting diode (OLED) displays.
Among the above flat panel displays, the OLED display using an organic light emitting diode generating light by a recombination of electrons and holes for the display of images has a fast response speed, is driven with low power consumption, and has excellent luminous efficiency, luminance, and viewing angle such that it has been spotlighted.
Generally, the organic light emitting diode display is classified into a passive matrix organic light emitting diode (PMOLED) and an active matrix organic light emitting diode (AMOLED) according to a driving method of the organic light emitting diode.
The passive matrix uses a method in which an anode and a cathode are formed to cross each other and cathode lines and anode lines are selectively driven, and the active matrix uses a method in which a thin film transistor and a capacitor are integrated in each pixel and a voltage is maintained by a capacitor. The passive matrix type has the simple structure and a low cost, however it is difficult to realize a panel of a large size or high accuracy. In contrast, with the active matrix type it is possible to realize a panel of a large size or high accuracy, however it is difficult to technically realize the control method thereof and a comparatively high cost is required.
In an aspect of resolution, contrast, and operation speed, the current trend is toward the active matrix organic light emitting diode (AMOLED) display where respective unit pixels selectively turn on or off.
However, the luminous efficiency is decreased by deterioration of the organic light emitting diode (OLED) such that the light emitting luminance is decreased for the same current.
Also, the current flowing in the organic light emitting diode according to the same data signal is changed by non-uniformity of the threshold voltage of the driving transistor controlling the current flowing in the organic light emitting diode and a deviation of the electron mobility.
The deterioration of the organic light emitting diode results in image sticking, and the characteristic deviation of the driving transistor results in mura.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.